1. Field of the Invention
The present invention relates to a signal processing circuit for use in a CD reproducing device for reproducing both CD-ROM data and audio data.
2. Description of the Related Art
Portable CD players are widely used as use of audio CDs is increased. Because the portable CD players are susceptible to external shocks which often result in reading errors, the players are usually provided with an anti-shock function.
Meanwhile, MP3 (MPEG Audio Layer-3; MPEG stands for Moving Picture Experts Group), an encoding format of audio data, is gaining widespread use. Such MP3 data is utilized in a manner that, for example, audio data encoded in MP3 format for compression using a personal computer is exchanged via Internet or the like, and that users enjoy music obtained by decoding the data in real time on the computer.
However, with widespread use of CD-Rs and CD-RWs, users increasingly enjoy music by playing a CD in which MP3 data is written as CD-ROM data with a player, and therefore attempts to provide a portable CD player with a function of playing a CD with MP3 data written therein are beginning to be made.
The anti-shock function is performed by storing a predetermined amount of read out audio data in a memory and outputting the audio data read out from the memory so that audio data can be continuously output even when the incoming audio data is interrupted. Thus, the memory for storing audio data is required to perform such a function. A memory is also required for the purpose of temporarily storing data during the process of decoding CD-ROM data read out from the CD. When a CD player for automobiles are provided with the anti-shock function, memories are required for the anti-shock function and CD-ROM decoding, as in the portable CDS.